Japan faces worst ‘slapped-cheek syndrome’ outbreak in 25 years, pregnant women at high risk

Japan is facing a significant outbreak of parvovirus B19 due to reduced post-pandemic immunity, posing significant risks to pregnant women and children

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A young woman with a rash on her face. Photo: Shutterstock

Published: 9:30am, 14 Dec 2024Updated: 9:32am, 14 Dec 2024

Health authorities in Japan have reported a sudden surge in parvovirus B19 infections, the worst outbreak in a quarter-century in parts of the country, raising fears that reduced post-pandemic immunity is fuelling its spread.

Parvovirus B19 causes erythema infectiosum, more commonly known as “slapped-cheek syndrome” because of the bright red cheek rashes it causes. Experts warn the virus can be especially dangerous for people with blood disorders and pregnant women who have not previously been infected.

The outbreak has become serious enough that Taiwan’s Centres for Disease Control issued a travel advisory on Tuesday, recommending that children and pregnant women avoid visiting the areas of eastern Japan most seriously affected.

“We still do not completely understand the reason for this sudden increase in cases,” said Dr Kazuhiro Tateda, president of the Japan Association of Infectious Diseases. “But of course it does come after the coronavirus pandemic, and we do know that these kinds of infectious diseases were quite strongly inhibited during that time, so it may be that many people now have less immunity to these kinds of infections.”

“We have also seen increases in cases of other types of similar illnesses, such as mycoplasma infections and influenza,” he told This Week in Asia, adding that it is “reasonable to believe” that while pandemic precautions benefited public health, illnesses are re-emerging as people become less careful and their immunity declines from reduced exposure.

Experts believe pandemic measures like wearing masks can reduce case of parvovirus B19 infections. Photo: Kyodo

According to the National Institute of Infectious Diseases, cases began to rise in August, with Tokyo and surrounding prefectures most severely impacted.